About Energy
In simple terms, energy can be thought of as the ability to do work. It can be kinetic, potential, electrical, chemical, nuclear, thermal, and many other forms, as well. Renewable energy and non-renewable energy are two types of energy.
What is the Unit of Energy?
In physics, we encounter various quantities having varying attributes, and describing them becomes difficult as we talk about the terms like energy, time, work, or any physical quantity that needs to have a standard measure to distinguish. In physics, the units determine the standard measure of these quantities. Such as if I say my aunt is 36 kg and she lives 1200 km from my city. Here, kg (for weight) and km (for distance) are the units to describe these physical quantities. Other examples are Kelvin for temperature; etc.
Because energy is defined in terms of work, the SI unit of energy is the joule (J), which was named after James Prescott Joule and his investigations on the mechanical equivalent of heat.
In more basic terms, 1 joule equals 1-newton meter and, in terms of SI base units.
\[1J = 1kg(\frac{m}{s})^{2} = 1(\frac{kgm^{2}}{s^{2}})\]
The unit of energy is the same as that of work (As work and energy are the two sides of the same coin).
The SI Unit of Potential Energy
'Potential energy' is how much power you have to do something. The more work you do, the more energy you need.
The potential energy is the energy stored in the matter. Therefore, the SI unit of potential energy is the same as the SI unit of all energies are given by,
\[1 J = 1 kg m^{-2} s^{-2}\] where the potential energy due to height is described as,
P.E. = mgh whose MKS unit is also kg \[m^{2} s^{-2} = 1 Joule\].
CGS Unit of Energy
An erg is a measure of energy that is equal to \[10^{-7}~J\]. An erg is the amount of work performed by a single dyne over a one-centimeter distance.
The CGS stands for centimeter-gram-second.
The CGS unit of energy is erg equivalent to \[1 g cm^{2} s^{- 2}\].
Ergs are a lot smaller than Joules, equivalent to \[10^{-7}~J\].
CGS Unit of Power
Power is defined as the rate of doing work given by,
Power = Work/time
The CGS unit of power is erg per second.
CGS Unit of Work
The CGS unit of work is Erg where 1 erg = 1 gm cm square/ second square.
The word erg is derived from the Greek word ergon (ἔργον) which means 'work' or 'task'.
One erg is also defined as the work done by a force of 1 dyne at a one-centimeter distance.
Unit of Energy in MKS System
The MKS stands for meter-kilogram-second.
1 Joule is equivalent to one Newton-meter (N-m) where 1 J is the amount of work done by a newton of force to a distance of 1 meter.
Where \[1 J = kg (m/s)^{2}\] = 1 Watt-second = 1 kg \[m^{2} s^{- 2}\].
So MKS unit of energy is kg \[m^{2} s^{- 2}\].
A force does the work to accelerate a body of mass 1 kg at the rate of \[1 ms^{-2}\].
Unit of Energy - Electricity
The kilowatt-hour (kWh) is a measure of electrical energy that is commonly used in utility bills; one kilowatt-hour is equal to 3.6 megajoules.
The SI Unit of Electrical Energy
The movement of charged particles inside the wire produces electricity. Electrical energy is the form of energy resulting from the flow of electrical charge is called electrical energy.
The SI unit of electrical energy is Joule symbolized as J.
1 Joule is equal to the energy transferred (or work done) when applying a force of one newton through a distance of one meter (1 newton-meter or N-m),
It is also defined as the work done in passing an electric current of one ampere through a resistance of one ohm for one second.
FAQs on Unit of Energy
1. What is energy? List the different forms of energy.
In physics, energy is a quantity that must be transferred on to the body to perform the work or any task as energy is defined via work.
There are two main forms of energy, namely, Potential energy (P.E), and Kinetic energy (K.E.). The energy is further classified into two types, namely renewable and non-renewable energy. Other forms of energy are:
Radiant energy
Sound energy
Elastic energy
Light energy
Motion energy
Gravitation energy
Nuclear energy
Electromagnetic energy
Mechanical energy
Wind energy
Biomass energy
Tidal energy
Geothermal energy
Hydroelectric energy
Wave energy
Hydrogen energy
Thermal energy
2. What do you mean by the law of conservation of energy?
The law of conservation of energy states that energy can never be created or destroyed but can be transformed into another form.
For example, when a box slides through a slop, at rest it has potential energy stored in itself when comes into motion that energy gets changed into kinetic energy. The friction acts in the opposite direction. Therefore, the kinetic energy from the box gets transformed into thermal energy that heats the box and the slope.
3. How is power related to work and energy?
Work is done by energy and the rate at which any task is done is called the power. Let’s take an example, suppose you’re driving a car. The air friction is trying to slow down your car, the engine is powerful enough to accelerate the car. So here the work done is equal to the force applied by an engine to a distance. Now the rate at which the engine does this work is called the power.
4. Why do physical quantities need units?
The units are important because, without units, we can never express physical laws precisely just from qualitative reasoning. Such as I am 8 but if I say I am 8 years old so years old is the unit to define the quantity age.
5. What unit of energy is used for Natural Gas?
Natural gas is frequently sold in energy content units or by volume. Joules or therms are common units for selling energy content. A therm is approximately 1,055 megajoules. The cubic meter or cubic foot are common units for selling by volume. In the United States, natural gas is sold in terms, which are equal to 100 cubic feet (100 ft3 = 1 Ccf).
Natural gas is sold in cubic meters in Australia. About 38 megajoules are contained in one cubic meter. Natural gas is marketed in gigajoules in most parts of the world.
6. What is the Law of Conservation of Energy?
A battery, for example, turns chemical energy into electrical energy, which can then be turned back into heat energy.
In a dam, potential energy is transferred to kinetic energy by moving water and a turbine, which is then converted to electric energy by a generator. According to the rule of conservation of energy, the total quantity of energy in a closed system, which corresponds to the sum of the system's constituent energy components, remains constant.
This law is derived from time translational symmetry, which implies that any physical process is independent of the time it began. Some works, and hence some sources of energy, are difficult to measure without assistance.
7. What are the different forms of Energy?
Below is the different forms of Energy:
Kinetic Energy: the energy of moving objects
The energy stored in the motion of objects is known as Thermal energy.
The energy of compression waves is known as Sound energy
The energy of moving charged particles is known as electrical energy.
Potential Energy (also known as stored energy) is the energy that an object has due to its position.
The energy held in chemical substances is referred to as chemical energy.
Nuclear energy is contained by the nucleus of an atom.
The energy of electromagnetic waves, such as light, is known as radiant energy.
8. Does the food industry also use units of energy?
The calorie is defined as the amount of thermal energy required to increase the temperature of one gramme of water by one degree Celsius from 14.5 degrees Celsius at 1-atmosphere pressure.
A calorie of 4.184 J is used in thermochemistry, but different calories, such as the International Steam Table calorie of 4.1868 J, have also been specified.
Food energy is measured in large calories or kilocalories equaling 1000 calories in various places and is sometimes capitalized as Calories. Food energy labelling in joules is required in the European Union, with calories often provided as a supplement.
9. What is termed Energy Loss?
When energy is transformed, moved, or transferred from one system to another, there is a corresponding loss of energy.
This indicates that some of the input energy is converted to a highly disordered form of energy, such as heat, when it is converted to a different form.
Unless one is actively turning energy into heat, it is nearly impossible to convert 100% of the incoming energy into output energy (like in a heater).
Furthermore, anytime electrical energy is transferred through power lines, the energy going into the lines is always greater than the energy coming out the other end. Processes will never be 100 percent efficient because of energy losses.
